This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-362601 filed on Nov. 29, 2000.
1. Field of the Invention
The present invention relates to an engine starting system for a vehicle that is operated by a high voltage power source to effectively compensate for the power consumed by a starter. Additionally, the invention provides a starting system for a vehicle equipped with an automatic stop and start system that effectively shortens a vehicle engine restarting time.
2. Description of Related Art
Generally, in a conventional vehicle, a starter is driven by a single power source. However, in recent years it has been discovered that as the electric load of a vehicle increases, a high voltage power source having an excellent energy recovery efficiency may be mounted in the vehicle in addition to the existing power source.
Electric starters on engines experience comparatively large electric power consumption amounts because they begin the rotation of the engine from a standstill. That is, engines have a high resistance to rotation or a large initial rotational inertia. The electric power consumed by the starter is compensated for by the electrical power generated by an engine driven generator.
Here, a charging efficiency is higher in the case where a high voltage power source is charged to a predetermined high voltage than in the case where the existing power source (low voltage power source) is charged to a predetermined low voltage. For this reason, when the starter consumes electric power from the high voltage power source having high charging efficiency, the consumed electric power can be compensated for more effectively.
Additionally, in order to improve the fuel consumption of the vehicle and to reduce exhaust gases, an automatic engine stop (idling stop) and start system, in which the engine is stopped while the automobile is stopped, has been instituted in recent years. This automatic engine stop and start system comprises monitoring the following: a vehicle speed, an accelerator opening amount, the state of a brake, and the like. Additionally, when the vehicle stops, the engine stops, and when the brake is released, the starter begins to start the engine, thereby starting the vehicle.
In the engine automatic stop and start system, an engine starting time range is required for starting the vehicle. For instance, in the situation when the vehicle waits at a traffic signal, the National Police Agency presented a report that if the time between waiting at a signal and starting the vehicle was long, it was predicted that traffic congestion would occur in urban areas where there is a large number of vehicles. Therefore, if the engine""s automatic stop and start system takes a long starting time to start the vehicle when the vehicle is waiting at a signal, the engine automatic stop and start system itself may be regulated by law. Therefore, it is urgently necessary to shorten an engine""s starting time.
The present invention has been made in view of the above circumstances. The first object of the present invention is to provide a starting system for a vehicle that is operated by a high voltage power source to effectively compensate for the power consumed by the starter. The second object of the present invention is to provide a starting system for a vehicle equipped with an engine automatic stop and start system, that will shorten a vehicle engine starting time. Therefore, when the starter motor can be operated by a high voltage power source, the starter motor will be operated by the high voltage power source, and when the starter motor cannot be operated by the high voltage power source, it will be operated by a low voltage power source. In this manner, the frequency of operation of the starter motor by the high voltage power source having a higher charging efficiency is increased and hence electrical power consumed by the starter can be efficiently compensated.
When a vehicle is started by an engine automatic stop and start system, the starter motor is operated by the high voltage power source. At this time, the engine is already warmed up and can be driven at high speeds by the starter motor to which high voltage is applied. Since the engine is driven at high rotational speeds, the engine can be started in a short time. As a result, it is possible to shorten the time required for starting the vehicle when the vehicle is waiting at a traffic signal, thereby preventing vehicle occupant stress normally caused by a slow starting engine, and preventing traffic congestion caused by the engine automatic stop and start system.
The control section of the engine automatic stop and start system may be mounted on an engine control unit which is provided separately from the starting control unit. The engine control unit may send a control signal to automatically stop and start the engine according to the current state of the vehicle governed by vehicle speed, braking force, and an accelerator position. When the starting control unit receives an automatic start signal from the engine control unit, it may switch the power source switching unit to the high voltage power source and pass an electric current through the starter motor. When a manually operated key switch is set at a starter position to start the engine, the power source switching unit may be switched to the low voltage power source.
A starting system for a vehicle may further include a magnet switch for connecting or disconnecting a current passing circuit of the starter motor wherein a current passing circuit of a coil of the magnet switch includes a unit for suppressing the amount of current passing through the coil. By providing the unit for suppressing the amount of current passing through the coil, the magnet switch slowly engages a contact. As a result, the magnet switch is prevented from bouncing against the contact and prevents an arc from being generated at the contact when high voltage is applied. Therefore, it is possible to prevent the contact of the magnet switch from being welded or broken thereby improving the reliability of the magnet switch. Further, since bouncing of the magnet switch is prevented, it is possible to prevent the occurrence of noises normally caused by bounces.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.